There are different views on the criteria for recognition of a small aortic annulus, with some considering a valve area index (VAI) <1.31 cm2/m2 or a valve diameter <19 mm as a valve/patient surface area mismatch; Ghosh et al [2] considered valve size indices (VSI) <12 mm/m2 as a valve/patient surface area mismatch. m2 is a valve/patient surface area mismatch. We used a valve size index <12 mm/m2 as a criterion to identify a small aortic annulus. In patients with small aortic annulus, matching the valve area to the patient's body surface area is essential to obtain a good hemodynamic outcome after surgery [3]. Aortic valve replacement with too small aortic valve will result in clinical symptoms of aortic stenosis remaining in the patient after surgery, which is prone to arrhythmias, left heart function impairment, and even sudden death; meanwhile, for adolescent patients, too small prosthetic valves will affect their growth and development and increase the risk of reoperation. For aortic valve replacement with small annulus, the surgical countermeasures are mainly: selection of stentless bioprosthetic valve, valve replacement on aortic annulus and valve replacement after widening of aortic annulus, and valve replacement after widening of aortic annulus is currently a more effective and practical surgical method. kitamura et al [4] compared the efficacy of 45 cases of small aortic annulus valve replacement after surgery and found that in long-term mortality and morbidity aortic annular widening surgery was significantly better than standard aortic valve replacement surgery. Currently, the main techniques for small aortic annulus widening are the Nicks method, the Manouguian method, and the Konno procedure [5-7]. With the Konno and Manougnian procedures, the aortic annulus diameter can be increased to 180% to 200% of the original diameter, whereas with the Nicks procedure it can be increased to 110%. We performed aortic annulus widening using a modified Manouguian's procedure. Compared with the Manouguian's procedure, our aortic incision downward without dissection of the left atrium and mitral valve leaflets was significantly simplified, and although it was not as extensive as the Manouguian's procedure, it allowed implantation of a valve of appropriate caliber with good results. Takakura et al [7] used a modified Nicks approach with a wide teardrop-shaped patch to widen the aortic annulus and tilted the valve slightly, allowing implantation of a 21# bileaflet valve at the aortic annulus where the 19 mm test ball could not pass. Our group used a modified Nicks method to widen the small aortic annulus similar to that of Takakura et al. A total of 11 cases of this procedure were performed, and similar surgical results were successfully achieved. the Konno's procedure is complex, with long operative time and many complications, the main complications include coronary septal penetration injury, conduction system injury causing atrioventricular conduction The main complications include atrioventricular conduction block due to coronary septal penetration injury, atrioventricular conduction block due to conduction system injury, and septal defect due to left and right ventricular traffic caused by torn sutures of septal patch. In this group, one case of Konno's operation was performed to treat left ventricular outflow tract stenosis and replace the mechanical valve of No. 19, and there was no coronary artery injury, no atrioventricular block, and no septal traffic after the operation, and good surgical results were achieved. In conclusion, aortic root widening is commonly performed by Manouguian, Nicks, and Konno methods, which can widen the small aortic annulus to a sufficient size to allow good hemodynamics after aortic valve replacement. the Manouguian method can widen the mitral annulus, aortic annulus, and ascending aorta at the same time, and the width of aortic root widening can reach 20-30 mm, which is clinically The Nicks approach focuses on widening the aortic annulus, which is simple and has limited application; the Konno approach is complex and has the risk of damaging the cardiac conduction system and coronary arteries and their important branches, so it is less commonly used clinically, but it is particularly suitable for cases with combined left ventricular outflow tract or subvalvular stenosis. Therefore, the appropriate aortic root widening method should be chosen according to the actual situation of the case in clinical practice.